Research: Could Birth-Canal Bacteria Help C-Section Babies?

From a poster at the recent Boston meeting of the American Society of Microbiology. (Courtesy Dr. Dominguez-Bello)
From a poster at the recent Boston meeting of the American Society for Microbiology. (Courtesy Dr. Dominguez-Bello)

The usual drill is to wipe the effluvia of birth off of newborn babies, cleaning them up and readying them for snuggling.

But in a fascinating departure, researchers have begun to experiment with the opposite: collecting birth-canal bacteria and wiping them onto babies after birth.

Why in the world? For good reason: to explore whether it might help babies delivered by C-section to restore some of the vaginal bacteria that they would have been exposed to if they'd gone through the birth canal.

Why do that? On the theory that altered bacterial populations could help explain why C-section babies tend to have higher odds of asthma, allergies, obesity and other health risks.

Dr. Maria Gloria Dominguez-Bello, an associate professor in the Human Microbiome Program at the NYU School of Medicine, presented some preliminary results on that research at a recent conference of the American Society for Microbiology here in Boston. Those initial findings suggest that indeed, using gauze to gather a mother's birth-canal bacteria and then impart them to babies born by C-section does make those babies' bacterial populations more closely resemble vaginally born babies — though only partially.

Many questions remain. But the research sounded so intriguing — and the intervention so simple, if it gains medical approval — that I asked Dr. Dominguez-Bello to discuss it. Our conversation, edited:

Your poster reports that there were six vaginal births, seven C-sections and four C-sections in which the babies also received the 'inoculum' of vaginal bacteria. But it wasn't clear to me: To what extent did the mothers' bacteria restore a more normal balance of bacteria in the C-section babies? A little or a lot?

When we analyzed the sharing — how many microbes any site of the baby’s body share with their mom’s vagina — we doubled the number of bacteria that the C-section babies were exposed to. But the vaginal process was six times as much. So the vaginal delivery still exposes the baby to a lot more.

In other words, if we got one bacteria in the C-section baby that is associated with the vagina, we got two in the inoculated C-section but six in the vaginal births. So those C-section babies still don’t have the full exposure of the vaginal babies.

That’s logical because during labor, the baby is rubbing against the mucosa of the birth canal for a long time and bacteria start growing even before the baby is out — growing and colonizing the baby during birth. In half an hour, you get multiplication of bacteria. If the baby gets one cell, an hour later the baby has probably four of those cells and five hours later, it's exponential.

Also, C-sections involve antibiotics. There is no C-section without antibiotics, and we don't know what the effect is of that gram of penicillin. If it’s good enough to kill strep B, I'm sure it's killing a lot more than that community of bacteria.

If your research pans out, using this gauze technique for C-section babies would seem to be such an easy intervention. I imagine there might already be women saying, 'I want to do that.' Possibly even, 'I want to schedule a C-section and do that.' What would you say to them?

I would say labor is a very complex process and labor is far more than inoculating the baby. And it’s a process that we don’t fully understand — what’s its adaptive value, why is it important?

There is a lot of stress in labor and some people think that stress is healthy for both the mother and the baby. It’s a long process, so during all those hours, physiological changes occur in the mom and the baby. So I think we have not studied labor enough and tried to understand what it is about labor that is healthy.

My little part is just trying to see how labor contributes to the microbiome. Natural birth includes the passage through a heavily inoculated canal. What I’m interested in studying is: what is the impact of not having that, and can we restore it?

People have asked me, 'Isn't your work going to stimulate C-sections instead of making mothers aware? People could say, 'Oh, fine, I'll have a C-section and use the gauze.' My response is that the microbes are just one part of labor and we don’t understand completely the whole process and why it is important.

Plus, with the restoration we did, we do restore the bacteria partially but not completely. And also, the mother's body prepares to breastfeed, for example — and who knows how many other things — much better after a natural birth than a C-section. A C-section is a sudden interruption of a process before the process finishes. So the body of the mother doesn’t even know that the baby’s out. It takes a while for the body to realize, 'Oh, there is no baby.' It’s really an insult to a process that ideally should end naturally, and only by necessity should it be interrupted.

It’s a little like antibiotics: We don't want to take antibiotics unless it is necessary, but sometimes it saves lives, of course. Then you do it. The problem is the abuse, it's thinking that there’s no cost. And so far, the point is, both moms and most doctors think there is absolutely no cost of C-sections, C-sections are okay. And we still don’t understand what the risk is. We haven’t quantified it in proper studies, it’s all associations so far, but we know that there is an association with higher risk of some diseases in babies that are born by C-section. So we need to do more research and in general, in life, we should respect nature.

You certainly don't want to encourage more C-sections, but for the women who must have C-sections, how soon would you think it would be reasonable to try the vaginal gauze and can you imagine any possible downsides?

The basic premise is that babies that should have crossed the birth canal, and for no medical reason they don't, then this is a restoring intervention. But we still, as with any vaginal delivery, we check for strep B; I would make sure the mother is HIV-negative, strep-B negative, and has an acid, lactobacillus-dominated vagina.

So far it's not a medical practice. It hasn’t been accepted as a standard practice. And it is not comparable to fecal transplant. Some people say, 'Well, isn't this considered similar to fecal transplant?' And I say, 'Absolutely not.' Fecal transplant is not a natural exposure. It works under certain circumstances, it saves lives, but it’s not natural. What we’re doing is not fecal transplant, it’s just exposing the baby partially to the natural environment the baby should have seen at birth.

So I don't know how much it will be regulated, if at all. Some people are doing it more or less individually, independently, because they believe it will be good for the baby. I had a C-section 23 years ago that now I consider was most likely unnecessary, and if I went back and I knew what I know now, I would do it, but the proper way: checking that I have a healthy microbial ecology in my vagina.

Some people get frustrated because their doctors don’t want to do it. This is the country of suing doctors and hospitals. From the medical point of view, it’s delicate. It’s the same when people ask me, 'Can you tell me how I should do it?' And I say, 'No, I cannot tell you that you should do it. This is not standard. What I can tell you is how I do my study. But again, I cannot recommend this because it’s a delicate issue. All I’m doing is studying.'

What's your next step in your research on the gauze intervention?

We’re increasing the number of babies. We already have 12 inoculated and we're publishing the work on this first little group just to publish the principle that it works as expected: of course, if you expose a baby to an inoculum, you get the inoculum in the baby. It’s a little simple but it’s important to show it works.

And we are doing the study in other countries. We've started in Bolivia, we're going to start it in Ecuador, in Stockholm and here, It’s still going on in Puerto Rico, and Chile has already started. So I hope to have a much bigger number of babies, and so far we’re following them for a year but maybe we’ll extend that.

Because you need to determine whether the bacterial restoration does affect the risk of diseases?

Yes. Ideally we’d have a big birth cohort study, and that’s a lot of money. To show the effect directly, to follow up prospectively and to study whether the kids develop asthma or not, that would be awesome but it’s a big study and needs funding. We’re doing this with very little funding.

Further reading: Missing Microbes: How Hard Should You Resist Antibiotics? And Why? 

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Carey Goldberg Editor, CommonHealth
Carey Goldberg is the editor of WBUR's CommonHealth section.



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